1. Field of the Invention
This invention relates to radiation monitors and more particularly to measuring instruments which can accurately monitor the radiation of electric fields resulting from both pulsed signals and continuous wave (CW) signals.
2. Description of the Prior Art
Semiconductor diode sensing elements are widely used in radiation monitoring instruments covering the lower range of frequencies of electrical fields from 0 through approximately 1.5 GHz, whereas thermocouple sensors operate most effectively over the frequency band ranging upward from approximately 300 MHz to 40 GHz and beyond. Diode sensors as well as thermocouple sensors are, therefore, required in any measuring system which covers the widest possible band width. It is now widely recognized that such radiation is harmful to humans and that the radiation surrounding certain frequencies of RF signals is more detrimental than at other frequencies.
Whereas thermocouple sensors respond accurately over their optimum frequency range to pulsed, variable CW and uniform-power CW signals, diode sensors do not. For example, radar signals having a characteristically short duty cycle can produce, particularly when the power level is high, substantial errors in diode sensors on the order of 10 to 100 times higher than CW signals of equal average power. Nevertheless, the existence of this error is scarcely recognized in the art and the cause of the error has not appeared in any literature known to the applicant. It follows that heretofore there has been no known way to eliminate the error.
The object of the invention, therefore, is to provide a diode sensor type instrument or probe for detecting and accurately measuring radiation surrounding electric fields where the inducing signals vary in their peak power, whether pulsed or variable CW.